The invention relates generally to lock systems and, more particularly, to an electronic lock system for allowing access to an individual unit of a multi-unit building.
Electronic locks are typically powered by either batteries or a wired power source. In the case of hotels, motels, inns, and the like, practically all electronic locks are battery powered. In either case, the functionality of these locks, particularly on guest room entry doors, are critical to the operation of the property.
For battery-powered locks, there is a significant purchase and labor expense associated with periodically replacing the batteries which is typically required about every two years. For hotels with standalone electronic lock systems, battery replacement scheduling must be performed on the basis of “shortest expected battery life span”, regardless of whether some batteries may have continued functioning for several months or even a year beyond the replacement point in time. For locks that are part of a centrally-controlled system, the expense can be slightly mitigated by locks which are able to report a low-battery condition. Batteries in such lock systems can then be replaced on an “as required” schedule, but there is still significant expense involved in monitoring these locks and then, as needed, physically replacing lapsed batteries.
For electronic locks that are powered from a wired source external to the door, there is a very significant initial installation cost, since the power source must be installed; wires must be run from that location to the periphery of the door, and doors must typically be core drilled to permit running the wires from the point on the periphery to the lock device itself. These systems also must rely on either flexible wiring on the hinged side of the door or dual contacts on one edge of the door which are mated to a second set of dual contacts on the door jam or strike plate. In either case, there is a mechanical failure rate inherent in the wired power supply, and there is also a significant risk that, if the power supply fails, the lock will cease functioning unless there is provision for a battery back-up, either in the lock or somehow interconnected with the external power source. There are also potential fire code problems related to altering doors by core drilling or otherwise changing the structure of the door.
In battery-powered electronic locks, it is estimated that 80% or more of power usage is related to maintaining the electronic circuitry needed to “read” the various types of access cards (e.g., magnetic stripe cards, smart cards and proximity cards), store access events in memory, operate LED indicators and so forth, and to normal battery leakage or self-discharge. The lock must be kept in a continuous standby state waiting for the next access card event to occur. In on-line systems, there is the added requirement to communicate various data via wireless means to and from some form of gateway or electronic relay device that is connected by wired or wireless means to a central computing server.
In these battery-powered locks, less than 20% of power usage is directly related to latching and unlatching activities. Such power usage, averaged over time, is on the order of 2 μA-10 μA.
In addition to the problem areas noted above, battery-powered electronic locks are typically bulky and not aesthetically pleasing. Principally, the bulkiness of the lock assembly is caused by the need to accommodate the battery pack (e.g., four AA batteries), an access card slot (for magnetic stripe and smart cards), and the circuitry needed to process and store entry and, in some cases, egress activities.
Therefore, a lock system is desired which requires less maintenance, uses reduced power, has fewer components, and is of minimal size.